Camera

ABSTRACT

An object of the present invention is to provide a camera capable of exactly displaying the number of residual films, even if there is concerned with such a situation that at the time when layered films remain in a film pack, the rear cover is opened and the film pack is re-mounted. The operational amplifier  236  is used to detect a current I M  conducting through the feeding motor  214 , and the detected current is subjected to the AD conversion by the MPU  220 . The display unit 61 displays a predetermined number corresponding to the number of films layered within the film pack having the shielding plate, or a number in which one is subtracted from the number of residual films stored in the storage section  210 , according as it is detected that now discharged one is the shielding plate.

TECHNICAL FIELD

The present invention relates to a camera on which a film pack adaptedfor accommodating layered instant photographic films is mounted.

BACKGROUND ART

Hitherto, there is known a camera on which a film pack adapted foraccommodating layered instant photographic films is mounted inside aframe member having an aperture, the film pack having such a structurethat the aperture of the frame member being closed by a shielding plate.In such a type of camera, there is one having a display unit fordisplaying the number of residual films within the mounted film packwherein when a new film pack is mounted, there is performed aninitialization processing such that the displayed content is alteredinto the number of films accommodated in the new film pack. Theshielding plate consists of a plastic member or the like having asufficient thickness since there is a need to provide a sufficientshielding property so as to protect the layered films from the externallight. After an exchange of film packs is performed, for example, at thetime when the rear cover is closed, the display unit displays apredetermined number (for example 10) corresponding to the number offilms layered within the new film pack, and upon receipt of an electricpower from a built-in battery, first the shielding plate is discharged.Thereafter, in accordance with a photographic operation, a top layer offilm of the layered films is exposed, so that a developer, which isstored in a part of the exposed film beforehand, is equally diffused inthe film to develop and discharged. As a result, the number of residualfilms is decreased by 1 and then displayed on the display unit.

According to the above-mentioned camera, when the rear cover is closedafter an exchange of the film packs, it is always decided that a newfilm pack is mounted, and the initialization processing is performed.For example, the display unit displays the number of films accommodatedin the new film pack. A photographer confirms the photography-possiblenumber of films through an observation of the number of films displayedon the display unit.

There is a case where a photographer performs such an operation that heerroneously opens the rear cover at the time when the layered filmsstill remain in the film pack, and he becomes aware of his error andthen immediately closes the rear cover. For example, the above-mentionedoperation is performed at the time when five sheets of layered filmsremain in the film pack, the camera decides, in view of the fact thatthe film pack is mounted and then rear cover is closed, that a new filmpack is mounted. According to such a type of camera, when a sheet offilm is discharged from the film pack, the camera decides that theshielding plate is discharged, and although the number of residual filmsis actually four sheet, the display unit displays the number of residualfilms ‘10’. For this reason, the conventional camera is associated witha problem that the number of residual films, which is actually possibleto be used for photography, is different from the number of residualfilms, which is displayed on the display unit.

DISCLOSURE OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide a camera capable of performing a proper control according to asituation, for example, in such a manner that in the event that at thetime when layered films remain in a film pack, the film pack isre-mounted, the number of the residual films is accurately displayed.

To achieve the above-mentioned object, the present invention provides acamera wherein a plurality of instant photographic films are layered, afilm pack having a shielding plate for shielding the layered films isloaded, the shielding plate is first discharged by a power of a built-inbattery and thereafter a top layer of film of the layered films isexposed in accordance with a photographic operation, and an exposed filmis discharged while developed, said camera comprising:

a shielding plate detection section for detecting a presence of theshielding plate of the loaded film pack; and

a control section for performing a control in accordance with adetection result by said shielding plate detection section.

According to the camera of the present invention, the presence of theshielding plate of the loaded film pack is detected. This feature makesit possible to distinguish the state in which a new film pack is loadedand the state that a film pack exchange operation is erroneouslyperformed on the film pack involved in photograph on halfway, and thenperform a proper control.

In the camera according to the present invention as mentioned above, itis preferable that said shielding plate detection section detectswhether one discharged by a present discharge operation is the shieldingplate, in accordance with the shielding plate of the loaded film pack ora load at the time of a discharge operation for the film.

The shielding plate is formed by a plastic member or the like having asufficient thickness, and the material of the shielding plate is largerin hardness and rigidity than the material of the film. For this reason,the load current of the feeding motor at the time of discharge of theshielding plate and the voltage drop due to the internal impedance ofthe built-in battery are larger than the load current at the time ofdischarge of the film and the voltage drop. Utilization of this featuremakes it possible to detect whether it is concerned with the shieldingplate through comparison of magnitude of the load current and thevoltage drop. In this case, as shown in the embodiments, which will bedescribed later, it is possible to use a relatively simple circuitstructure.

In the camera according to the present invention as mentioned above, itis preferable that the camera further comprises a display unit fordisplaying a state of the camera, and said control section controls adisplay content of said display unit in accordance with a detectionresult by said shielding plate detection section.

As states of the camera, there are raised states of a counter forstoring the number of films, a film speed, a lens position, anelectronic flash control mode (on/off/auto) as the exposure mode, and anexposure correction (darken/normal/lighten). The control as mentionedabove makes it possible to distinguishably display the state of thecamera at the time when the new film pack is loaded and the state of thecamera in half way of photography.

In the camera according to the present invention as mentioned above, itis preferable that the camera further comprises a display unit fordisplaying the number of residual films within the loaded film pack,

wherein said control section comprises a storage section for storing thenumber of residual films within the film pack before a film packexchange operation, and a display control section for causing saiddisplay unit to display a predetermined number corresponding to thenumber of films layered within the film pack having the shielding plate,or a number in which one is subtracted from the number of residual filmsstored in said storage section, according as said shielding platedetection section detects that now discharged one is the shieldingplate, in a case where the film pack exchange operation is made.

The above-mentioned “film pack exchange operation” includes not only theoperation wherein the loaded film pack is removed and a new film pack isloaded, but also an operation wherein the loaded film pack is removedand the removed film pack is loaded as it is, and an operation whereinan operation (for example, an operation of opening the rear cover) forremoving the film pack is performed, and an operation (for example, anoperation of closing the rear cover) for completing the loading of thefilm pack is performed without removing the film pack.

According to this arrangement, in the event that the shielding plate isdischarged, the display unit may display a predetermined numbercorresponding to the number of films layered in a new film pack. And inthe event that a film is discharged, the display unit may display thenumber in which one is subtracted from the number of residual filmsstored in the storage section. For this reason, even if it is concernedwith such situations that at the time when layered films remains in thefilm pack, an exchange operation is performed on the film pack, it ispossible to exactly display the number of residual films on the displayunit, without bringing about, as in the former camera, such a situationthat the photography-possible number of residual films is different fromthe number of residual films displayed on the display unit.

In the camera according to the present invention as mentioned above, itis acceptable that said camera adapts for loading thereonto a film packrecording film information related to an incorporated film, and

said camera has a sensor for reading the film information recorded onthe film pack, and said control section causes said sensor to read thefilm information upon receipt of that said shielding plate detectionsection detects the shielding plate.

Here, the film information related to an incorporated film implies thenumber of films stored in the film pack, and a film speed.

This arrangement makes it possible to perform a control of a camera inaccordance with the film information read by the sensor.

Further, in the camera according to the present invention as mentionedabove, it is acceptable that said control section performs aninitialization on at least one portion of element of said camera uponreceipt of that said shielding plate detection section detects theshielding plate.

Here, it is preferable that “at least one portion of element” referencedabove is one or more among a lens position, an electronic flash controlmode as the exposure mode, and an exposure correction. Upon receipt ofthat the shielding plate is detected, the initial setting is performedon “at least one portion of element”. This feature makes it possible toenhance an operational efficiency.

As mentioned above, according to the present invention, it is possibleto perform a proper control according to a situation, for example, insuch a manner that in the event that at the time when layered filmsremain in a film pack, the film pack is re-mounted, the number of theresidual films is accurately displayed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing an external appearance of a cameraaccording to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an external appearance of thecamera shown in FIG. 1.

FIG. 3 is a rear elevation of the camera according to the firstembodiment in which a rear cover is opened.

FIG. 4 is a view showing loads in various types of operational sequenceof the camera according to the first embodiment, and set up thresholds.

FIG. 5 is a circuit diagram of the camera of the first embodiment.

FIG. 6 is a circuit diagram of a camera of a second embodiment of thepresent invention.

FIG. 7 is a front view showing an external appearance of a cameraaccording to a third embodiment of the present invention.

FIG. 8 is a rear elevation of the camera shown in FIG. 7 in which a rearcover is opened.

FIG. 9 is a circuit diagram of the camera of the third embodiment.

FIG. 10 is a schematic diagram of a film pack in its entirety.

FIG. 11 is a view showing combinations of signals based on a film speednotch provided on the film pack shown in FIG. 10 and film speedsassociated with the combinations.

FIG. 12 is a flowchart useful for understanding a control routine in thecamera of the third embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described with reference tothe accompanying drawings.

FIG. 1 is a front view showing an external appearance of a cameraaccording to a first embodiment of the present invention. FIG. 2 is aperspective view showing an external appearance of the camera shown inFIG. 1.

A camera 10 is an instant camera. To take a photograph, when both edgesof a front cover 11 are grasped and picked up, a lens 20 provided at thecenter of the camera 10 is projected forward in FIG. 1 and diagonallyforward in FIG. 2.

On an upper portion 31 of a camera main frame 30, there are provided anelectronic flash unit 309 for emitting an electronic flash light, an AFunit 310 comprising an AF light-projection window 311 incorporatingtherein a light-emitting device for the auto focus (AF) and an AF lightreceiving window 312 incorporating therein a light receiving element forreceiving light from the light-emitting device, and a finder 313. At theleft side of a lens 20 in FIGS. 1 and 2, there is provided an AE unit320. The AE unit 320 has an AE window 321 for transmitting light to abuilt-in AE sensor for an exposure control. On the upper portion of theAE window 321, there is provided a slide switch 322 for applying afilter effect to the AE window 321. At the lower portion of theelectronic flash unit 309, there are provided a slide switch 323 to beused at the time of self-timer photography and a self-window 324incorporating therein a light-emitting device for emitting light at thetime of self-timer photography.

Further, at the left of the front view and the perspective view shown inFIG. 1 and FIG. 2, respectively, there is provided a grip portion 33,which will be held by a photographer at the time of the photography. Atthe top of the grip portion 33, there is provided a shutter button 34.

Furthermore, also at the right of the front view and the perspectiveview shown in FIGS. 1 and 2, respectively, there is provided a gripportion 35 inside which there is installed a built-in battery 40 fordriving the camera 10. At the top of the built-in battery 40, there isprovided a circuit substrate 200 for performing a control of the camera10 in its entirety. The circuit substrate 200 will be described later.Further, the camera 10 is provided with a feeding motor for feeding ashielding plate for a film pack and a film, which will be also describedlater.

FIG. 3 is a rear elevation of the camera according to the firstembodiment in which a rear cover is opened.

The camera 10 shown in FIG. 3 shows a state that the rear cover 50 isopened and the film pack 100 is mounted. At the upper right of FIG. 3 asto the camera 10, there is provided a film pack detection switch 60 fordetecting whether a film pack 100 is loaded. As shown in FIG. 3, in astate that the film pack 100 is loaded, the film pack detection switch60 is pushed by the film pack 100 into a turn-on condition. Thus, it isdetected that the film pack 100 is loaded. At the upper left of the filmpack detection switch 60, there is provided a rear cover switch 51 fordetecting whether a rear cover 50 is closed. When the rear cover 50 isclosed, the rear cover switch 51 is pushed and turns on. Thus it isdetected that the rear cover 50 is closed. Further, at the right of thefilm pack detection switch 60, there are provided a display unit 61 fordisplaying the number of residual films within the loaded film pack 100,and an electronic flash charging switch 62 for performing the emissionof an electronic flash light. Furthermore, adjacent to the finder 313,there is provided a lamp window 63 for indicating electronic flashcharging completion through blinking.

FIG. 4 is a view showing loads in various types of operational sequenceof the camera according to the first embodiment, and set up thresholds.

A shield plate discharge sequence is for discharging a shielding plateformed by a plastic member or the like having a sufficient thickness.For this reason, as shown in FIG. 4, the load involved in the shieldplate discharge sequence is the largest one of the loads involved in thevarious types of operational sequences. The film discharge sequence isfor transporting a film by a plurality of rollers for instance so that adeveloper is equally diffused in the film to develop. Accordingly, thefilm discharge sequence belongs to the larger sort in load of thevarious sorts of operational sequences. However, the load involved inthe film discharge sequence is smaller than the load involved in theshield plate discharge sequence, since the material of the shieldingplate is larger in hardness and rigidity than the material of the filmdischarge sequence. An electronic flash charge sequence needs a largepower for performing an electronic flash charge. Accordingly, theelectronic flash charge sequence is large in load after the shield platedischarge sequence. Hereinafter, a shutter driving sequence, an AFoperational sequence and an AE arithmetic operational sequence arelarger in load in the named order. FIG. 4 further shows a threshold setup between the load involved in the shield plate discharge sequence andthe load involved in the film discharge sequence. The threshold will bedescribed referring to FIG. 5.

FIG. 5 is a circuit diagram of the camera of the first embodiment.

In FIG. 5, a power source switch 218 is disposed adjacent to thebuilt-in battery 40. The power source switch 218 is closed when a frontcover 11 is raised as shown in FIG. 2.

An MPU 220 is installed in the circuit substrate 200 for performing acontrol of the camera 10 in its entirety. A storage unit 210 isconnected to a bus terminal BUS of the MPU 220. The display unit 61, theelectronic flash unit 309, the AF unit 310, and the AE unit 320 areconnected to a port PA, a port PB, a port PC and a port PD,respectively. The film pack detection switch 60, the rear cover switch51, the shutter button 34 are connected to a port PE1, a port PE2 and aport PE3, respectively.

A motor drive section 230 is provided with a transistor 231 for drivinga feeding motor 214, and an operational amplifier 236 for detecting acurrent I_(M) conducting through the transistor 231. A port PE4 of theMPU 220 is connected to a gate of the transistor 231 via a resistance232 constituting the motor drive section 230. An emitter of thetransistor 231 is connected to the ground GND. A collector of thetransistor 231 is connected via a resistance 235 to a non-invertinginput of the operational amplifier 236 and the feeding motor 214. Aninverting input of the operational amplifier 236 is connected via aresistance 234 to the ground GND, and is connected via a resistance 233to an output of the operational amplifier 236 and an AD conversion inputterminal AD of the MPU 220. A feeding switch 215 is connected to a portPES of the MPU 220. The feeding switch 215 is closed when the feedingmotor 214 rotates to discharge the shielding plate or a film.

The storage unit 210 stores the number of residual films in the filmpack before an exchanging operation of the film pack 100.

The display unit 61 displays the number of residual films in the loadedfilm pack 100.

The portion including the operational amplifier 236 and the ADconversion input terminal AD of the MPU 220 corresponds to an example ofthe shielding plate detection section referred to the present invention.The use of the portion including the operational amplifier 236 and theAD conversion input terminal AD of the MPU 220 makes it possible todetect the presence of the shielding plate of the loaded film pack.

The MPU 220 is further provided with a display control section forcausing the display unit 61 to display, when an exchange operation forthe film pack 100 is made, a predetermined number corresponding to thenumber of films layered the film pack with a shielding plate, or anumber that is obtained when one is subtracted from the number ofresidual films stored in the storage unit 210, according as it isdetected or not that now discharged one is the shielding plate. Thisdisplay control section and the storage unit 210 corresponds to thecontrol section referred to the present invention.

According to the camera 10 thus constructed, when the front cover 11 israised, voltage V_(B) of the built-in battery 40 is applied via thepower source switch 218 to a capacitor 211, a regulator 212 and thefeeding motor 214. The regulator 212 stabilizes the entered voltageV_(B) and creates voltage V_(c). The created voltage V_(c) is applied toa capacitor 213 and a power source terminal V_(CC) of the MPU 220. Here,there is described a case where a photographer performs such anoperation that he erroneously opens the rear cover 50 at the time whenthe layered films still remain in the film pack 100 loaded onto thecamera 10, and he becomes aware of his error and then immediately closesthe rear cover 50. Since the film pack detection switch 60 is closed, an‘L’ level of signal is fed to the port PE1 of the MPU 220. Also, sincethe rear cover switch 51 is closed, an ‘L’ level of signal is also fedto the port PE2 of the MPU 220. In the state that an ‘L’ level of signalis fed to both the port PE1 and the port PE2, the MPU 220 stands byuntil the shutter button 34 is pushed.

The shutter button 34 is pushed in the state that the film pack 100 isproperly loaded and the rear cover 50 is also properly closed. Then, an‘L’ level of signal is fed to the port PE3 of the MPU 220. Upon receiptof the ‘L’ level of signal, the MPU 220 generates an ‘H’ level of signalfrom the port PE4. The ‘H’ level of signal is fed via the resistance 232to the transistor 231, so that the transistor 231 turns on wherebycurrent I_(M) conducts through a path of the built-in battery 40→thepower source switch 218→the feeding motor 214→the resistance235→transistor 231→the ground GND. Thus, the feeding motor 214 rotatesto start a discharge of films. Since the current I_(M) conducts throughthe resistance 235, a voltage (potential) by the product of the value ofthe resistance 235 and the current I_(M) is generated between both theends of the resistance 235. The voltage thus generated is fed to theoperational amplifier 236 to be amplified with a predetermined gain, andthen fed to the AD conversion input terminal AD of the MPU 220. In theMPU 220, the entered voltage is subjected to an AD conversion to obtaina digital value D_(F). The digital value D_(F) corresponds to themagnitude of the load in the film discharge sequence shown in FIG. 4.The MPU 220 has a digital value D_(TH) corresponding to the thresholdshown in FIG. 4. In the MPU 220, the digital value D_(F) is comparedwith the digital value D_(TH). Since the digital value D_(F) is smallerthan the digital value D_(TH), the display control section of the MPU220 causes the display unit 61 to display the number of films that isobtained when one is subtracted from the number of residual filmsaccommodated in the film pack. This number of films is stored in thestorage unit 210.

On the other hand, in the event that the shutter button is depressed ina state that a new film pack 100 is loaded and the rear cover 50 isclosed, the current I_(M) conducts through the path which is the same asone mentioned above, so that the feeding motor 214 rotates to start thedischarge of the shielding plate, and a voltage is generated betweenboth the ends of the resistance 235. This voltage is fed via theoperational amplifier 236 to the AD conversion input terminal AD of theMPU 220, so that the voltage is subjected to the AD conversion in theMPU 220 and whereby the digital value D_(s) is created. Further, in theMPU 220, the digital value D_(s) is compared with the digital valueD_(TH). The digital value D_(s) corresponds to the load in the shieldplate discharge sequence. On the other hand, the digital value D_(TH)corresponds to the threshold shown in FIG. 4. Thus, the digital valueD_(s) is larger than the digital value D_(TH). Accordingly, it isdetected that the now discharged one is the shielding plate, and thedisplay control section of the MPU 220 causes the display unit 61 todisplay the number of films accommodated in the new film pack. Further,this number of films is stored in the storage unit 210.

In this manner, according to the camera 10 of the first embodiment, inthe event that the new film pack 100 is loaded and the rear cover 50 isclosed, the number of films accommodated in the new film pack isdisplayed on the display unit 61. On the other hand, in the event thatthe rear cover 50 is once opened at the time when the layered filmsstill remain in the film pack 100, and then closed, the number ofresidual films is displayed on the display unit 61. Accordingly, ithappens, as in the conventional camera, no such a matter that the numberof residual films, which is actually capable of being photographed, isdifferent from the number of residual films, which is displayed on thedisplay unit. Thus, it is possible to perform a proper display control.

Incidentally, according to the first embodiment, there is explained anexample in which to detect the shielding plate of the loaded film pack,the operational amplifier 236 is used to detect a current I_(M)conducting through the feeding motor 214, and the detected current issubjected to the AD conversion by the operational amplifier 236.However, the present invention is not restricted to this embodiment. Itis acceptable that the current I_(M) conducting through the feedingmotor 214 is converted into ‘H’ level or ‘L’ level of signal by acomparator and the converted signal is fed to the port of the MPU 220.

FIG. 6 is a circuit diagram of a camera of a second embodiment of thepresent invention.

In FIG. 6, the same reference numbers denote the same parts as those ofFIG. 5, and the redundant explanation will be omitted.

According to the circuit structure shown in FIG. 5, the shielding plateof the loaded film pack is detected in accordance with the currentconducting through the feeding motor 214, and a control for the displayand the like is performed in accordance with the detection result. Onthe other hand, according to the circuit structure shown in FIG. 6, theshielding plate of the loaded film pack is detected in accordance withan amount of voltage drop of a voltage appearing between both theterminals of the built-in battery 40, and a control for the display andthe like is performed in accordance with the detection result.

Since the built-in battery 40 has an internal impedance R_(Z), thevoltage V_(B) between both the terminals of the built-in battery 40 ismore lowered, as the larger load is driven. Accordingly, the voltageV_(B) between both the terminals of the built-in battery 40 is morelowered in the event that the load in the shield plate dischargesequence is driven, as compared with a case where the load in the filmdischarge sequence is driven. The present embodiment of the presentinvention has been made in view of the above-mentioned point. Accordingto the present embodiment, there is provided a circuit structure that aresister 241 and a resister 242 are connected in series between both theends of the capacitance 211 to which the voltage V_(B) of the built-inbattery 40 is applied, and the connected point is connected to the ADconversion input terminal AD of the MPU 220. When such a circuitstructure is adopted to measure an amount of voltage drop of the voltageV_(B) between both the terminals of the built-in battery 40 by the ADconversion section of the MPU 220, it is acceptable to provide a controlfor causing the display unit 61 to display a predetermined numbercorresponding to the number of films layered the film pack with ashielding plate, or a number that is obtained when one is subtractedfrom the number of residual films stored in the storage unit 210,according as it is detected or not that now discharged one is theshielding plate.

FIG. 7 is a front view showing an external appearance of a cameraaccording to a third embodiment of the present invention. FIG. 8 is arear elevation of the camera shown in FIG. 7 in which the rear cover isopened.

In FIGS. 7 and 8, the same reference numbers denote the same parts asthose of FIG. 1.

In a camera 410, as compared with the camera 10 shown in FIG. 1, thereare omitted the slide switch 322 for applying a filter effect to the AEwindow 321, and the slide switch 323 to be used at the time ofself-timer photography. As shown in FIG. 8, a film pack 110, which willbe described, is loaded on the camera 410. Further, there is provided adisplay unit 60 at the right of the film pack detection switch 60. Atthe lower portion of a display unit 70, there are provided a self-timerswitch 81, an exposure correction switch 82 and an electronic flashcontrol switch 83.

The self-timer switch 81 is for setting up a time for self-timerphotography. When the self-timer switch 81 is pushed once, a time forself-timer is set up, and a pattern (not illustrated), which indicatesthat the time set up is performed, is displayed on the display unit 70.And when the self-timer switch 81 is pushed again, the set up time isreleased, and the patter is erased in display.

The exposure correction switch 82 is for indicating a degree of anexposure correction. Whenever the exposure correction switch 82 isdepressed, a cursor 71 displayed on the display unit 70 is shifted tothe positions of characters D (darken)→N (normal)→L(light), which areprinted at the left of the display unit 70.

The electronic flash control switch 83 is for controlling an emission ofelectronic flash light. Whenever the electronic flash control switch 83is depressed, a cursor 72 displayed on the display unit 70 is shifted tothe positions of characters O (on)→F (off)→A(auto), which are printed atthe right of the display unit 70.

The display unit 70 displays the number of films and a film speed aswell as the above-mentioned patterns, and the cursors 71 and 72.

FIG. 9 is a circuit diagram of the camera of the third embodiment.

FIG. 9 shows an MPU 221 connected to the built-in battery 40. Storagesection 210 is connected to a bus terminal BUS of the MPU 221. Thestorage section 210 is provided with a display-processing counter (notillustrated) for storing the number of films. Connected to ports PA1,PA2 and PA3 of the MPU 221 are a self-timer switch 81, an exposurecorrection switch 82 and an electronic flash control switch 83,respectively. Connected to ports PA4 to PA7 of the MPU 221 is thedisplay unit 70. Connected to ports PB, PC and PD of the MPU 221 are anelectronic flash unit 309, an AF unit 310 and an AE unit 320,respectively. Further, Connected to ports PE1, PE2, PE3, PE4, PES, andPE6 of the MPU 221 are a rear cover switch 51, a power source switch218, a shutter button 34, a first notch switch 101, a second notchswitch 102, and a film pack detection switch 60, respectively. The firstnotch switch 101 and the second notch switch 102 corresponds to anexample of a sensor for reading film information stored in the filmpack, referred to in the present invention.

The MPU 221 is in a stand-by mode in a state that the front cover 11 isclosed. When the front cover 11 is raised so that the power sourceswitch 218 is closed, the port PE2 of the MPU 221 receives a ‘L’ levelof signal so that the MPU 221 shifts to the usual operation mode. Whenthe front cover 11 is closed, the MPU 221 shifts to the stand-by mode.Even in the state that the front cover 11 is closed, when the rear cover50 is opened once and then closed after the film pack 110 is loaded,both the film pack detection switch 60 and the rear cover switch 51 areclosed. As a result, the ports PE6 and PE1 of the MPU 221 receive a ‘L’level of signal so that the MPU 221 shifts to the usual operation mode.Thus, as will be described later, discharge of the shielding plate ordischarge of a film is performed, and thereafter the MPU 221 shifts tothe stand-by mode.

A motor driver 250 is provided with transistors (not illustrated) eachfor driving a feeding motor 214 and a barrel driving motor 216. Thosetransistors are connected to the ports PF2 and PF4 of the MPU 221,respectively. A feeding switch 215 and a barrel switch 217 are connectedto the ports PF1 and PF3 of the MPU 221, respectively. The feedingswitch 215 is closed at the time when the feeding motor 214 rotates sothat the shielding plate or a film is discharged. The barrel switch 217is a switch for far-and-near switching, which is closed at the time whenthe barrel driving motor 216 rotates so that a lens arrives at apredetermined position. Connected to an AD conversion input terminal ADof the MPU 221 is an operational amplifier (not illustrated) fordetecting a current conducting through the feeding motor 214. The filmpack 110 is loaded on the camera 410 thus constructed.

FIG. 10 is a schematic diagram of a film pack in its entirety. FIG. 11is a view showing combinations of signals based on a film speed notchprovided on the film pack shown in FIG. 10 and film speeds associatedwith the combinations.

The film pack 110 shown in FIG. 10 has such a structure that a pluralityof instant photographic films is layered in a frame 111 having anaperture 111 a in form of a photographic field, and the aperture 111 aof the frame 111 is shut by a shielding plate 112. The shielding plate112 and a film (not illustrated) are discharged in a direction A shownin FIG. 10. In the event that a film having a film speed other than ISO400, ISO 800 and ISO 1600 is incorporated in the film pack 110, bothfirst and second film speed notches 113 and 114 are formed at the sideof the frame 111. In the event that a film having a film speed of ISO400 is incorporated in the film pack 110, only the first film speednotch 113 is formed at the side of the frame 111. In the event that afilm having a film speed of ISO 800 is incorporated in the film pack110, only the second film speed notch 114 is formed at the side of theframe 111. In the event that a film having a film speed of ISO 1600 isincorporated in the film pack 110, none of the first film speed notch113 and the second film speed notch 114 is formed at the side of theframe 111.

The first notch switch 101 and the second notch switch 102 are disposedadjacent to the portion of the frame 111 in which the first film speednotch 113 and the second film speed notch 114 is formed. In this manner,the first notch switch 101 and the second notch switch 102 are disposedat the same side of the frame 111. This feature makes it possible tosimplify an arrangement and wiring for the first notch switch 101 andthe second notch switch 102.

In the event that a film having a film speed other than ISO 400, ISO 800and ISO 1600 is incorporated in the film pack 110, both first and secondfilm speed notches 113 and 114 are formed at the side of the film pack110. Thus, both the first notch switch 101 and the second notch switch102 turn on, and as shown in FIG. 11, ‘L’ level of signals are outputtedfrom the first notch switch 101 and the second notch switch 102. In theevent that a film having a film speed of ISO 400 is incorporated in thefilm pack 110, only the first film speed notch 113 is formed at the sideof the film pack 110. Thus, the first notch switch 101 and the secondnotch switch 102 turn on and turn off, respectively, and ‘L’ level ofsignal and ‘H’ level of signal are outputted from the first notch switch101 and the second notch switch 102, respectively. In the event that afilm having a film speed of ISO 800 is incorporated in the film pack110, only the second film speed notch 114 is formed at the side of thefilm pack 110. Thus, the first notch switch 101 and the second notchswitch 102 turn off and turn on, respectively, and ‘H’ level of signaland ‘L’ level of signal are outputted from the first notch switch 101and the second notch switch 102, respectively. In the event that a filmhaving a film speed of ISO 1600 is incorporated in the film pack 110,none of the first film speed notch 113 and the second film speed notch114 is formed at the side of the film pack 110. Thus, both the firstnotch switch 101 and the second notch switch 102 turn off, and ‘H’ levelof signals are outputted from the first notch switch 101 and the secondnotch switch 102.

Next, there will be described an operation of the camera 410 of thethird embodiment referring to FIG. 9 and FIG. 12.

FIG. 12 is a flowchart useful for understanding a control routine in thecamera of the third embodiment.

First, there will be described a case where a new file pack 110 isloaded in a state that the front cover 11 (cf. FIG. 7) is closed.

Even if the MPU 221 is in the stand-by mode, in which the front cover 11is closed, when the rear cover 50 is once opened and then closed afterthe new film pack 110 is loaded, both the film pack detection switch 60and the rear cover switch 51 are closed, so that an ‘L’ level of signalis fed to both the port PE6 and the port PE1 of the MPU 220, and a modeis shifted from the stand-by mode to the usual operational mode. Thus,of the control routines shown in FIG. 12, a routine for a rear coverclosing processing is executed.

First, in a step S4, an exposure processing and a shutter control areperformed. In the exposure processing, an electronic flash control modeis set up to an off-side, and a shutter is controlled by a dummy value.Then, the process goes to a step S5 in which a film discharge processingis performed. In the film discharge processing, an ‘H’ level of signalis outputted from the port PF2 of the MPU 221 shown in FIG. 9 to themotor driver 250, so that the feeding motor 214 rotates. Here, since thenew film pack 110 is loaded, a discharge of the shielding plate isinitiated, and in a similar fashion to that explained referring to FIG.5, an analog signal according to the load of the shielding plate is fedvia the operational amplifier (not illustrated) to the AD conversioninput terminal AD of the MPU 221 and is subjected to the AD conversionin the MPU 221. Thus, it is detected that now discharged one is theshielding plate.

Next, in a step S6, it is determined whether the shielding plate isconcerned. Here, it is determined that the shielding plate is concerned,and thus the process goes to a step S8 in which an initializationprocessing for a camera is performed. For the initialization processing,a lens position is set up to a position (a short-range view side)suitable for an instant camera which is often associated with ashort-range view photograph. The electronic flash control mode is set upto an auto-side, and the exposure correction is set up to a normal-side,so that the exposure mode is cleared.

Next, in a step S9, the MPU 221 reads the signals on the ports PE4 andPE5 and causes the storage unit 210 to store a film speed. The camera410 is a camera of a system capable of receiving thephotography-possible number of films. In the camera 410, thephotography-possible number of films is stored in the display-processingcounter of the storage unit 210 through means not illustrated. In thismanner, the camera 410 recognizes film information comprising the filmspeed and the number of films. Next, the process goes to a step S10 inwhich the display unit 70 displays the number of films layered in thenew film pack 110 and the film speed. Further, in order to inform anoperator of the state of the initially set up exposure correction(normal) and the electronic flash control mode (auto), the cursors 71and 72 (cf. FIG. 8) of the display unit 70 are shifted to characters Nand A, respectively, and thus the routine is terminated. Thereafter, theMPU 221 shifts to the stand-by mode. In this manner, when the new filmpack 110 is loaded onto the camera 410 and the rear cover 50 is closed,the presence of the shielding plate is detected, and the initial set upfor the camera 410 is performed in accordance with the detection result.Therefore, the operation of an operator is simplified and an operationalefficiency is enhanced. Further, at the time point when the rear cover50 is closed, the shielding plate is discharged, and thus an operatorcan immediately perform photography. Accordingly, it is possible toprevent an operator from missing the shutter chance.

Next, to perform photography, the front cover 11 is raised. When thefront cover 11 is raised, the power source switch 218 is closed, so thata ‘L’ level of signal is fed to the port PE2 of the MPU 221. Uponreceipt of the ‘L’ level of signal, the MPU 221 shifts from the stand-bymode to the usual operational mode. When the shutter button 34 isdepressed, a ‘L’ level of signal is fed to the port PE3 of the MPU 221.Since the film pack detection switch 60 is closed, the ‘L’ level ofsignal is fed to the port PE6 of the MPU 221. Further, since the rearcover switch 51 is also closed, the ‘L’ level of signal is fed to theport PE1 of the MPU 221. Upon receipt of the ‘L’ level of signals, theMPU 221 executes a routine for a release processing of the controlroutines shown in FIG. 12.

First, in a step S1, a luminance of a camera subject is measured byphotometry means, and a shutter control operation is performed inaccordance with a setting condition of the film speed, the exposurecorrection value, and the electronic flash control mode, which areinitially set up in the above-mentioned rear cover close processingroutine, and also a decision of needs of emission of the electronicflash light is performed.

Next, in a step S2, a subject distance is computed by focusing means toperform an arithmetic operation for a lens position control, and theprocess goes to a step S3.

In the step S3, a shooting lens is moved to a predetermined position inaccordance with an operation result in the step S2. In detail, an ‘H’level of signal is outputted from the port PF4 of the MPU 221 shown inFIG. 9, so that the barrel driving motor 216 rotates in accordance withthe operation result and thus the shooting lens is moved to apredetermined position.

In the step S4, a shutter control is performed in accordance with thephotometry result in the step S1, and in the event that an emission ofthe electronic flash light is performed, the light emission control isalso performed. Next, the process goes to the step S5 in which the filmdischarge processing is performed. In the film discharge processing, an‘H’ level of signal is outputted from the port PF2 of the MPU 221 shownin FIG. 9 to the motor driver 250, so that the feeding motor 214 rotatesto start a discharge of films. In a similar fashion to that explainedreferring to FIG. 5, an analog signal according to the load of the filmsis fed via the operational amplifier (not illustrated) to the ADconversion input terminal AD of the MPU 221 and is subjected to the ADconversion in the MPU 221. Thus, it is detected that now discharged oneis the film.

Next, in the step S6, it is determined whether the shielding plate isconcerned. Here, it is determined that the film is concerned, and thusthe process goes to a step S7 in which ‘1’ is subtracted from thedisplay processing counter. Then, this routine is terminated. In thismanner, the photography is performed.

There is a case where the rear cover 50 is once opened at the time whenthe layered films still remain in the film pack 100, and then closed.When the rear cover 50 is closed, the above-mentioned rear cover closeprocessing routine is executed. In this case, since a top layer of film,which is layered in the film pack, is exposed, the film is discharged inthe step S5, and in the step S6 it is decided that the film isconcerned, and then the process goes to the step S7 in which the valueof the display processing counter is subtracted by ‘1’. Thus, thisroutine is terminated. In this manner, the exposed film is discharged.

Incidentally, according to the present embodiment, as mentioned above,from the viewpoint that the shutter chance is not missed, there isprovided that the shielding plate is discharged at the time when therear cover is closed. For this reason, for example, even in the eventthat a film pack, which has a film speed different from a film packhaving a desired film speed, is loaded, and an operator is aware of hiserror before photography and wishes to exchange the film pack for a filmpack having a desired film speed through opening and closing operationsof the rear cover, the film is exposed. Thus, in practice, it is notpermitted to perform the opening and closing operations of the rearcover until the films are completely used. In view of the foregoing, itis acceptable to provide such a control that a discharge of theshielding plate is not performed at the time when the rear cover isclosed, but is performed in the release processing routine that iscarried out when the shutter button is depressed. This control makes itpossible to freely perform the opening and closing operations of therear cover, since the shielding plate is not discharged at the time whenthe new film pack is loaded.

What is claimed is:
 1. A camera wherein a plurality of instantphotographic films are layered, a film pack having a shielding plate forshielding the layered films is loaded, the shielding plate is firstdischarged by a power of a built-in battery and thereafter a top layerof film of the layered films is exposed in accordance with aphotographic operation, and an exposed film is discharged whiledeveloped, said camera comprising: a shielding plate detection sectionfor detecting a presence of the shielding plate of the loaded film pack;and a control section for performing a control in accordance with adetection result by said shielding plate detection section.
 2. A cameraaccording to claim 1, wherein said shielding plate detection sectiondetects whether one discharged by a present discharge operation is theshielding plate, in accordance with the shielding plate of the loadedfilm pack or a load at the time of a discharge operation for the film.3. A camera according to claim 1, further comprising a display unit fordisplaying a state of the camera, wherein said control section controlsa display content of said display unit in accordance with a detectionresult by said shielding plate detection section.
 4. A camera accordingto claim 2, further comprising a display unit for displaying the numberof residual films within the loaded film pack, wherein said controlsection comprises a storage section for storing the number of residualfilms within the film pack before a film pack exchange operation, and adisplay control section for causing said display unit to display apredetermined number corresponding to the number of films layered withinthe film pack having the shielding plate, or a number in which one issubtracted from the number of residual films stored in said storagesection, according as said shielding plate detection section detectsthat now discharged one is the shielding plate, in a case where the filmpack exchange operation is made.
 5. A camera according to claim 1,wherein said camera adapts for loading thereonto a film pack recordingfilm information related to an incorporated film, and wherein saidcamera has a sensor for reading the film information recorded on thefilm pack, and said control section causes said sensor to read the filminformation upon receipt of that said shielding plate detection sectiondetects the shielding plate.
 6. A camera according to claim 1, whereinsaid control section performs an initialization on at least one portionof element of said camera upon receipt of that said shielding platedetection section detects the shielding plate.